Making your choice based on pump configuration narrows your search down to three types of air compressors:
i. Lightweight Compressors: These are made up of a universal motor and an air-cooling system. The cooling system increases the life of the unit. Lightweight compressors are suitable for casual applications such as air-gun cleaning and tire-inflation.
ii. Direct-drive Compressors: They are oil-free with a standard induction motor. Since they are oil free, these units are not ideal for commercial uses and are commonly put to moderate uses in homes. Direct-drive compressors are normally pre-lubricated, mostly with Teflon and when they are put in constant use, the Teflon wears out reducing the life of the unit quite drastically.
iii. Belt-drive Compressors: These units require constant oiling which makes them quieter than their direct-drive counterparts. Therefore, the units are ideal for commercial uses where constant air-compression is required. They can last up to three times longer than the direct-drive models and are easy to repair.
The current market offers two types of belt-drive compressors: single-stage compressors and two-stage compressors. Compressed air is delivered directly to the tank with single-stage compressors while the two-stage units pass the pressurized air through two cylinders before delivering it to the main tank. The first is a low-pressure cylinder that pumps the air into the second, high-pressure smaller cylinder which then delivers the air into the tank. Two-stage air compressors create an ample supply of highly pressurized air required in such appliances as air drills and spray guns.
Most of the two-stage compressors are cooled between the stages to reduce excessive heating. Air compressing exudes heat, and the units must have as less heat as possible for more efficiency. However, you should not confuse stages for cylinders and it is possible to buy a single-stage unit with two cylinders.
The size of the compressor tank is another important factor to consider when selecting a unit. Tanks vary in size ranging from small two-gallon tank to huge commercial 240 gallon models. Small tanks are ideal for a tool like impact wrench or other short-burst tools. Sand blasters, paint equipments and other high-air-compression tools may require a bigger tank. If you are having trouble choosing between two comparable units, go for the one that has a larger tank.
The size of the tank determines the general size of the unit. If you have space concerns and still need a big tank, a vertical model could be the better choice than a horizontal model.
Your source of power might also influence your choice of an air compressor. An electric powered unit is ideal if you have a reliable electrical connection. Electric models are more common and tend to cost slightly lesser than other models. If you cannot trust your electric power source, then a gas powered unit is in order. The gas powered air compressors are equally reliable as their electric counterparts and can be used anywhere. However, avoid operating a gas powered aid compressors in an ill-ventilated workshop, it is a health hazard.
The performance and length of life of your air-compressor depends on the amount of care extended to the unit;
- Check for tank-moisture accumulation daily.
- Check the oil level at least weekly.
- Keep the motor and pump fins dirt free.
- Always check the safety valve and to ensure it is place.
- Lubricate the motor as constantly as possible.
- Inspect and replace the belt(s), pressure gauge, safety valves and other parts as constantly as necessary.